the Slim-G shown in one of your pictures seems to be very popular in the UK. I have read some posts here about Slim Jim, J pole, flowerpot and extendable HT antennas.
It might be somewhere in the reflector, but I have not found a 1:1 comparison with an A/B switch between the Slim-G and a flowerpot (which I am using). According to the website of Spectrum Communications (“Actually the aerial described as a J pole is really a misnomer as it really is a squashed letter G, hence the new name.”) The Slim-G seems to be very similar to a Slim Jim (unless there is something special in the grey tube apart from a choke and/or mechanical connection).
When I read the reports about the Slim-G, their owners seem to be very satisfied but I would like to know if it really outperforms a flowerpot under the same conditions.
I haven’t performed an A/B test with the Slim-G and any of my other 2m antenna’s.
In general, without any scientific tests, it seems that receive is better than my other Slim Jim antennas.
I think this is my third one, as the unit does take a hammering in a storm / strong winds.
Whilst the tube is not heavy, even with weatherproofing and additional support, the top section where the cable enters the unit is where most harm is done.
Hence I don’t use it anymore in bad weather.
Not sure if there are others who have performed any tests, but it’s a popular SOTA antenna.
There are a lot of different names for these antennas but what really matters is the antenna size in wavelengths and how efficient the feed and matching system is. In general I think it is valid to say that all half wave antennas exhibit similar gain and the main thing that distinguishes them from each other are the feed method and mechanical structure, some requiring more complex mounting arrangements than others. An awkward antenna requiring specific cable entry or dressing is not as easy to use for SOTA as one that has simpler requirements.
The idea that a flowerpot half wave dipole necessarily requires a PVC tube is not correct. I carry one with me in my backpack, it is rolled up and carried in a bag, We tagged this style of flowerpot as the “naked flowerpot” and it is supported on a thin telescopic pole.
I am sometimes a bit confused by the terminology. Just to quote spectrumcomms.co.uk again: „Portable Aerial based on the ‘Slim Jim’, 3/4 wave End Fed Vertical.“. My understanding up to now was that one quarter belongs to the matching section and that the radiator is actually an EFHW.
I am still not convinced that there is anything special about the grey pipe. Probably it is just the housing for a sealed mechanical connection and/or a choke. I did find an alternative design but do not know if this has ever been widely used.